The AP (college-level) Biology students at my high school were given an assignment. They must keep two fish, a white cloud and an algae eater (not sure what species) alive in a contained ecosystem in a 1 gallon, unfiltered tank. They aren't allowed to change the water, add a filter, or add anything to the water. It's impossible to create a self-contained ecosystem in a tiny tank, let alone a 1 gallon, which isn't suitable for any fish whatsoever, not even a betta. My friend is upset because her fish is dying, and it's no wonder. I wonder about the teacher of this class. I can't believe he actually assigned his students to subject fish to improper living conditions.